It's literally exactly what you said...?

It does appear to be what you are saying. The linked article is discussing how common it is For schools to lock young children in tiny rooms by themselves.

One room in the article is described as 3x3x7 and another is even smaller at 5 sq feet. These are literally the rooms we are discussing and that you are defending using for timeouts.

Edit: It appears from your edit that you simply may have not read the article and thus did not realize what you were endorsing.